Colorectal cancer screening with fecal immunochemical testing in Nigeria
Authors: Onyema Greg Chido-Amajuoyi
Journal: The Lancet Global Health (2022)

Olusegun Alatise and colleagues (July, 2022)1Alatise OI Dare AJ Akinyemi PA et al.Colorectal cancer screening with fecal immunochemical testing: a community-based, cross-sectional study in average-risk individuals in Nigeria.Lancet Glob Health. 2022; 10: e1012-e1022Summary Full Text Full Text PDF PubMed Scopus (4) Google Scholar did a cross-sectional study of colorectal cancer screening with fecal immunochemical testing among average-risk individuals in Nigeria. This study is welcome given the marked paucity of studies examining this important cancer prevention modality throughout Africa and the absence of quality data on colorectal cancer screening in Nigeria. It is well documented that colorectal cancer screening rates in Africa are significantly suboptimal.2May FP Anandasabapathy S Colon cancer in Africa: primetime for screening?.Gastrointest Endosc. 2019; 89: 1238-1240Summary Full Text Full Text PDF PubMed Scopus (15) Google Scholar Therefore, scholarly work that sheds light on this important topic must be encouraged. The authors of the study conclude that although screening with fecal immunochemical testing in Nigeria is feasible and acceptable to average-risk asymptomatic participants, because of the low positive predictive value for advanced neoplasia and high endoscopy burden investigating false positives, fecal immunochemical testing might not be an appropriate screening tool. Given the implications of the study's conclusion, we seek further clarification on several issues. It is reported that participants with a positive fecal immunochemical test underwent a follow-up colonoscopy at one centre in each study state by trained endoscopists. However, several questions arise, particularly on how colonoscopy quality and findings were validated. Quantifying the quality of screening colonoscopy is known to be challenging, with variations in the ability of endoscopists to detect suspicious lesions well documented. As a result, several scales and quality measures have been developed to enhance the validity and reliability of colonoscopy outcomes research.3Lai EJ Calderwood AH Doros G Fix OK Jacobson BC The Boston bowel preparation scale: a valid and reliable instrument for colonoscopy-oriented research.Gastrointest Endosc. 2009; 69: 620-625Summary Full Text Full Text PDF PubMed Scopus (792) Google Scholar, 4Sáenz-Fuenzalida R Riquelme-Pérez A Díaz-Piga L et al.The challenge of quantifying screening colonoscopy quality: development and psychometric properties of the colonoscopy quality score instrument.Rev Gastroenterol Mex (Engl Ed). 2022; 87: 297-304PubMed Google Scholar Factors such as the adenoma detection rate, bowel preparation scales (eg, the Boston bowel preparation scale), and colonoscopy withdrawal time are known to affect colonoscopy results,5Corley DA Jensen CD Marks AR et al.Adenoma detection rate and risk of colorectal cancer and death.N Engl J Med. 2014; 370: 1298-1306Crossref PubMed Scopus (1280) Google Scholar, 6Barclay RL Vicari JJ Doughty AS Johanson JF Greenlaw RL Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.N Engl J Med. 2006; 355: 2533-2541Crossref PubMed Scopus (1132) Google Scholar and highlight potential sources of variation in colonoscopy outcomes. Epidemiological tools that could have further enhanced robustness of study findings include the assessment of inter-rater and intrarater reliability. The authors report that the quality of bowel preparation was recorded. However, these data were not reported. Contextually, colonoscopy quality assessment takes heightened importance for a study done in Nigeria for several reasons, including endoscopist-related factors such as variation in training and specialisation among endoscopists and years of experience. Equipment-related factors include age, sophistication, and reliability of the scopes used in each centre. The performance of endoscopies in Nigeria is not specialty dependent. In some countries, the performance of oesophagogastroduodenoscopies and colonoscopies are limited to gastroenterologists; however, in Nigeria, this procedure is also done by general surgeons. Given that the study was not nationally representative, the external validity of the study is brought into question with the conclusion that fecal immunochemical testing might not be an appropriate screening tool in Nigeria. Study findings are limited to the states of Osun, Kwara, and Lagos. Nigeria is a largely heterogeneous country, and the people's sociodemographic characteristics (including education, socioeconomic status, and religion) are known to be strong predictors of health behaviours and outcomes.7Chido-Amajuoyi OG Wonodi C Mantey D Perez A Mcalister A Prevalence and correlates of never vaccinated Nigerian children, aged 1–5 years.Vaccine. 2018; 36: 6953-6960Crossref PubMed Scopus (9) Google Scholar This holds particularly true for northern Nigeria, which is not represented in this study. I declare no competing interests. Colorectal cancer screening with fecal immunochemical testing: a community-based, cross-sectional study in average-risk individuals in NigeriaColorectal cancer screening with qualitative fecal immunochemical tests in Nigeria is feasible and acceptable to average-risk asymptomatic participants. However, the low positive predictive value for advanced neoplasia and high endoscopy burden investigating false positives suggests it might not be an appropriate screening tool in this setting. Full-Text PDF Open AccessColorectal cancer screening with fecal immunochemical testing in Nigeria – Authors' replyWe thank Onyema Greg Chido-Amajuoyi for their letter and agree that colonoscopy quality is an important component of any colonoscopy-based study. The colonoscopies in our study1 were done by five experienced endoscopists. They are members of the Society of Gastroenterology and Hepatology in Nigeria, an affiliate body of the World Gastroenterology Organization that provides guidelines for endoscopy in Nigeria. All endoscopists have at least 5 years of experience in routine colonoscopy, and most had done more than 1000 colonoscopies before the study. Full-Text PDF Open Access